Controller and control method for internal combustion engine

A method of controlling a vehicle internal combustion engine having a crankshaft connected to a manual transmission via a clutch, the method comprising:

• executing a feedback process of calculating a feedback operation amount, which is an operation amount used to perform feedback control to set a rotational speed of the crankshaft of the internal combustion engine to a target rotational speed;
• executing a torque control process of controlling a torque of the internal combustion engine by using, as an input, an idle required torque, which is a value obtained by multiplying a base torque by a correction coefficient;
• executing an assist process of raising the base torque by an assist torque, which is a torque used to limit a decrease in the rotational speed of the crankshaft that accompanies transition of the clutch from a disengaged state to an engaged state;
• executing a fixing process of fixing the correction coefficient at a specified value on condition that the clutch is in a transition period from the disengaged state to the engaged state;
• and
• executing a gradual decrease process of stopping the fixing process and gradually decreasing the correction coefficient to the feedback operation amount when the fixing process is executed and the assist torque is smaller than or equal to a predetermined value.

A controller for an internal combustion engine being configured to control a vehicle internal combustion engine having a crankshaft connected to a manual transmission via a clutch, wherein

• the controller comprises processing circuitry, and
• the processing circuitry is configured to execute
• a feedback process of calculating a feedback operation amount, which is an operation amount used to perform feedback control to set a rotational speed of the crankshaft of the internal combustion engine to a target rotational speed;
• a torque control process of controlling a torque of the internal combustion engine by using, as an input, an idle required torque, which is a value obtained by multiplying a base torque by a correction coefficient;
• an assist process of raising the base torque by an assist torque, which is a torque used to limit a decrease in the rotational speed of the crankshaft that accompanies transition of the clutch from a disengaged state to an engaged state;
• a fixing process of fixing the correction coefficient at a specified value on condition that the clutch is in a transition period from the disengaged state to the engaged state;
• and
• a gradual decrease process of stopping the fixing process and gradually decreasing the correction coefficient to the feedback operation amount when the fixing process is executed and the assist torque is smaller than or equal to a predetermined value.